Charney's target article convincingly demonstrates the need for the discipline of quantitative human behavior genetics to discard its false assumptions and to employ the techniques, assumptions, and research program characteristic of modern developmental psychobiology.

Research pragmatics, not a defective conceptual framework, supports modern biological reductionism. Conducting research to reveal the casual web underlying the multiple developmental pathways leading to any species-specific characteristic requires better research techniques than those commonly used. It takes much patience, time, and effort to gain even small glimpses of an answer to any developmental question.

Ontogenetic factors constrain the evolution of species-typical traits. Because human infants are born “prematurely” relative to other primates, the development of handedness during infancy can reveal important ontogenetic influences on handedness that may have contributed to the evolution of the human species-typical trait of a population-level right-hand dominance.

The procedures used to ensure reliable occurrences of the A-not-B error distort and miss essential features of Piaget's original observations. A model that meshes a mental event, highly restricted by testing procedures, to the dynamics of bodily movement is of limited value. To embody more than just perseverative reaching, the formal model must incorporate Piaget's essential features.